Rubber tapping hand tool— Study on Ergonomics and Product design
©All rights reserved Pratheek Punchathody 2019
Project Brief
To design and develop an effective, ergonomic hand tool for natural rubber tapping which can prevent ulnar deviation that causes carpel tunnel syndrome and also to reduce musculoskeletal disorder.
Introduction
Natural rubber cultivation is one of the major agricultural occupation in western coast of Karnataka and parts of Kerala in India. Rubber is also a major crop in many of the countries such as Malaysia, Indonesia, Srilanka. Rubber tapping is one of the major work involved in harvesting the natural rubber.
Currently In practice there are two types of traditional knife is being used — Jabong Knife and V-Groove Knife.
This study is to understand the user, design and develop of ergonomic hand tool for rubber tapping and the evaluation of the same.
Problems Identified
Rubber tapping is an occupation with a high risk for developing carpal tunnel syndrome (CTS). Exposure to excessive ulnar deviation and wrist flexion, among other risk factors, contributes to increased carpal tunnel pressure contributing to the development of carpal tunnel syndrome.
Natural rubber extraction also requires a major skills for tapping the trees as the cut that is made to the tree for extracting the natural rubber is critical. The wrong cut to the tree may damage the tree which may also kill the tree.
Understanding the habitat
Habitat study is done in the rubber estate along with the owner of the estate and the rubber tapping professionals. The current practice and the tools used for rubber tapping is studied.
Location : Biliyoor, 50 Km from Mangalore
Total Farm : 8 Acres of Rubber plantation
Age of Trees : 7 Years
Owner : Mr. Sathyanarayana
The habitat study is done to understand the rubber plantation, the workplace in which the people extract the natural rubber, Current hand tools in practice, current methods followed and also to understand the challenges faced by the rubber tappers and the plantation owners in the rubber cultivation.
User Interaction
“It’s very difficult to get a skilled labor for rubber tapping these days. Skilled labors charge very high charges for tapping. On top of money we need to give them the share in the latex as well. It is very hectic job for me to tap the trees as the proper tools are not available. Unless the tapper is skilled, one cannot tap the latex out of the tree as there is a risk of damaging the tree” — Mr. Sathyanarayana Bhat
“I have been practicing rubber tapping from past 35 Years. As I remember my first toy was a rubber tapping tool as it was out family profession. Tapping requires a lot of skill to cut the tree. If it is a wrong cut then it will damage the tree to the extent of killing the tree. I tap around 500- 600 trees a day. The tool we use is hand made tool. I personally suffer from chest and shoulder pain because of the force I apply. ” — Mr. Suji Joseph
Literature Study
Research Paper — 1 : Ergonomic rubber tapping knife relieves symptoms of carpal tunnel syndrome among rubber tappers
Research Paper — 2 : Design and testing of a Semi Automatic Rubber Tree Tapping machine
Research Paper — 3 : Musculoskeletal problems and ergonomic risk assessment in rubber tappers: A community-based study in southern Thailand
Research Paper — 4 : Effect of Hand tool shape on hand performance, usability and discomfort using trowel.
The literature study gave the insights in the current innovations that are done in the field of natural rubber cultivation, the problems validated from the ergonomic point of view. This also the reference and guideline to approach the problem and solve it.
Observations from the study
Angle of the cut with the horizontal is 30 Degree
Height of the cut 1.5mm
Depth of the cut is 1.5mm
Cambium should not be damaged
Tapping is done in early morning before sunrise
Tappers do tap about 400–500 trees per day
Hilly plantation area
Tapping must be done before sunrise
High force to be applied to hand tool to cut the bark
Thickness of the bark varies from one tree to other
Severe Ulnar deviation in the wrist with traditional tool
Repetitive to and fro work
Rubber tapping is done during early in the morning before sunrise. This is in practice as the maximum amount of latex is extracted early in the morning.
Variations of handle grip angle
The angle of the handle grip of the hand tool is one of the major parameter in preventing the ulnar deviation of the hand. The variations of the handle grip is prototyped with the angle of 30, 45 and 75 degree. The hand grip variations are tested with the user to understand the ulnar deviation variations in the hand while holding the hand tool in position.
Usability testing for the hand grip angle
The ergonomic literature is referred to understand the length of the hand grip, diameter of the grip, shape of the grip and few other parameters. Once the variations are fixed based on the user study, prototyping and from the literature, the mechanism that actually cuts the tree is decided.
Prototyping the concepts
Two concepts are sketched based on the understanding from the habitat and the users. Then the selected concepts are prototyped using the soft materials such as foam boards and wood to visualize the concepts.
Functional Prototype
The functional prototype of the hand tool is manufactured using the mild steel. The blade which has to cut is tempered to retain the sharpness. Hand grip is manufactured using wood (user feed back from the study to use wood instead of plastic or rubber).
Testing the grip strength
The handle grip strength is detected using the force sensitive resistor. A hand glove is developed which has force sensitive resistor attached to it. Arduino is the controller module which is used for processing and plotting the data. When the hand tool is held in hand and used, the force applied by the hand on hand tool is measured and plotted.
Usability testing
The functional prototype is manufactured based on the concepts and multiple user testing is performed to iterate the complete process and to refine the prototype.
The major goal of the hand tool is to make sure that the user requires less skill to perform the rubber tapping without having a fear of damaging the tree and also to prevent ulnar deviation that causes carpel tunnel syndrome.
Conclusion
From the study and analysis it is observed that the deviation in the hand is reduced while using the newly designed hand tool.
- The hand eye interaction is reduced as the depth of the cut is fixed by the mechanism of new hand tool. There is no fear of harming the tree.
- The adjustment for the depth of the cut will be an added advantage for the user while using the hand tool.
***In the process of Patenting***
©All Copyrights Reserved : Pratheek Punchathody, 2019
